The invention pertains to a compression driver or phase plug, and particularly to a compression driver having substantially equal input and output aperture areas and substantially straight acoustical paths there between.
Compression drivers, on horn loaded loud speaker systems are known. The function of a phase plug within a compression driver is to provide an acoustic path which reduces out of phase acoustic signals and destructive cancellation or interference. However, efficient and satisfactory operation of such loud speaker systems is difficult to achieve.
In order to understand this, it is necessary to look at the acoustic principles involved. A compression driver is designed to increase the efficiency of a loud speaker by compressing the acoustical energy and transferring it through a channel to the throat of a horn. Many iterations of compression and channeling have been performed in the past. For instance, there are compression drivers with annular rings (circumferential slit), radial slits (tangerine-like sections) and hole array phase plugs. The purpose of the phase plug is to compress the audio and to equalize the acoustic path lengths to thereby minimize high frequency cancellations caused by phase differences. These prior arrangements have not resulted in a completely satisfactory transformation of the acoustic signal and in particular have not resulted in transformations without high frequency interference.